1. Field of the Invention
The present invention is generally directed to a unique lacing mandrel for use when lacing a stator.
2. Description of the Related Art
The construction of laced stators, used in electric motors, is well known. These stators have a number of metallic laminates stacked together to form a core. The stator core forms an annulus having a central opening, or bore, as it is typically called. A number of slots, spaced evenly around the stator bore, extend through the stator core. Each slot opens to the stator bore via a corresponding small channel.
Wedges, typically made of Mylar, line each slot. Particularly, each slot has one wedge (or liner) which generally lines the inner periphery of the slot, and another wedge, positioned in the slot, covering the small channel which opens to the stator bore.
Windings are wound through the slots, according to conventional winding techniques, and thus extend from opposite ends of the stator core. The windings are laced with string to hold the windings as close as possible to the core ends.
A known and considerable problem in the manufacture of laced stators is that, during normal lacing operation, the wedges in the slots of the stator core are undesirably moved from their original position by the lacing needles. Particularly, those wedges covering a channel are forced through their respective channel, thus forcing the wedges into the stator bore. Since a stator having wedges extending into its bore is unacceptable, an operator is required to reset the wedges, after lacing, with a wedge-set machine. While the addition of this step is undesirable, it is necessary to the manufacture of a useful, laced stator. Additionally, a visual inspection of the stator must be performed, following the wedge-set process, to insure that the wedges are clear of the stator bore.
The undesirable necessity to reset the wedges, following lacing of a laced stator, creates yet an additional problem in the manufacture of laced stators. Resetting the wedges typically pushes the windings of the stator beyond acceptable limits, thus requiring an additional manufacturing step of hammering the windings back down toward the ends of the stator core.
Accordingly, the need exists for a device which prevents stator slot wedges from being forced into the stator bore during the lacing operation. Such a device would prevent the need to reset the wedges, and then reposition the windings. The need also exists for a device used when lacing stators which prevents the additional need to visually inspect the stator bore to certify that wedges are clear of the bore. The present invention meets these needs, and overcomes the drawbacks of the prior art.